This invention relates to a container for free-flowing, fluid and like materials, comprising a tubular outer envelope that can be closed at both ends and a tubular inner member which at at least four positions spaced about the circumference of the tubular outer envelope is connected to said outer envelope, said inner member having a length that is 30-100% of the height of the container.
A similar container is described in applicants co-pending U.S. "Pat. application Ser. No. 053,614 filed May 26, 1987."; There, the provision of the inner member that is connected to the outer envelope results in a container which is characterized by high dimensional stability and a very high stacking strength, even when relatively flexible and weak material is used, as, for example, paper. These particular properties are obtained by causing deformative and stacking forces to be absorbed by tensile forces generated in the inner member in the circumferential direction. When regularly stacked together and loaded, this container is very satisfactory. In the case of high to very high loads, problems may occur under particular conditions, for example, owing to the inner member becoming torn as a result of local diagonally directed forces, for example, from slightly warped or misaligned stacking, or from inertia forces during deceleration of a vehicle loaded with containers.
It is an object of the present invention to improve the strength of a container of the above kind still further, so that the container is sufficiently strong and dimensionally stable to resist extreme and non-uniform loading conditions as outlined above.